Electric arc furnaces are well known for melting scrap metal for recycling purposes. An arc furnace is an exothermic apparatus the heat energy for which is generated by the flow of electrical current through one or more arcs internal to the furnace.
One common problem associated with electric arc furnaces, is the problem of "flicker" (i.e. voltage disturbances in a supply network arising from large and rapid fluctuations in load current during certain stages of the furnace and at frequencies up to 25 Hz). The severity of flicker may be rated as a function of the difference between short circuit KVA to operating KVA.
Software voltage control has been used in the past to reduce flicker in DC and AC systems (see L. Gyugyi and R. H. Otto, "Static Shunt Compensation for Voltage Flicker Reduction and Power Factor Correction", Proceedings of the American Power Conference, Vol. 38, pp. 1271-1286, 1976, and W. E. Staib, N. G. Bliss and R. B. Staib, "Neural Network Conversion of the Electric Arc Furnace", Steel Making Conference Proceedings, pp. 749-756, 1991).
Shunt type compensators (static VAR compensators) have been proposed for flicker reduction (see J. M. Wikston, "Static VAR Compensation of Voltage Flicker From Arc Furnaces", CEA Report No. 0427818m 1993), which describes the difficulties of such systems in eliminating flicker.
None of these prior art systems provides series type A.C. current control or predictive control on direct current.